atomic weight
noun
: the mass of one atom of an element
specifically
: the average mass of an atom of an element as it occurs in nature that is expressed in atomic mass units see Chemical Elements Table
Examples of atomic weight in a Sentence
Recent Examples on the Web
Previous molecules detected on Mars were smaller, meaning their atomic weight was less than the molecules found in the new study, and simpler.
—
Ashley Strickland, CNN Money, 29 Mar. 2025
This is sent through an enrichment process, usually in gas centrifuges, where it is turned into gaseous form and centrifuged till the two isotopes are separated from each other due to their slight difference in their atomic weights.
—Jacek Krywko, Ars Technica, 10 June 2024
That number is the atomic weight—the total number of protons and neutrons in the nucleus of the atom.
—Rhett Allain, WIRED, 23 Feb. 2024
Hydrogen was the focus of the earlier work because its low atomic weight influences the behavior of vibrations within the material in a way that promotes the formation of superconducting pairs of electrons.
—John Timmer, Ars Technica, 4 Aug. 2023
Also in the 1860s, the English chemist John Newlands became the first to order the elements according to atomic weight — a strategy that Mendeleev and others followed until the early 1900s, when the discovery of atomic numbers presented a more precise measure.
—Cody Cottier, Discover Magazine, 12 Apr. 2022
The second is the atomic weight.
—Andrew Moseman, Discover Magazine, 18 Dec. 2010
Many periodic tables include the atomic number (number of protons) and atomic weight (which depends on protons and neutrons).
—Bill Andrews, Discover Magazine, 26 June 2019
Specific trends, such as melting point and atomic radius, recur periodically among the elements when they’re listed in order of increasing atomic weight.
—Bill Andrews, Discover Magazine, 26 June 2019
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Ashley Strickland, CNN Money, 29 Mar. 2025
This is sent through an enrichment process, usually in gas centrifuges, where it is turned into gaseous form and centrifuged till the two isotopes are separated from each other due to their slight difference in their atomic weights.
—Jacek Krywko, Ars Technica, 10 June 2024
That number is the atomic weight—the total number of protons and neutrons in the nucleus of the atom.
—Rhett Allain, WIRED, 23 Feb. 2024
Hydrogen was the focus of the earlier work because its low atomic weight influences the behavior of vibrations within the material in a way that promotes the formation of superconducting pairs of electrons.
—John Timmer, Ars Technica, 4 Aug. 2023
Also in the 1860s, the English chemist John Newlands became the first to order the elements according to atomic weight — a strategy that Mendeleev and others followed until the early 1900s, when the discovery of atomic numbers presented a more precise measure.
—Cody Cottier, Discover Magazine, 12 Apr. 2022
The second is the atomic weight.
—Andrew Moseman, Discover Magazine, 18 Dec. 2010
Many periodic tables include the atomic number (number of protons) and atomic weight (which depends on protons and neutrons).
—Bill Andrews, Discover Magazine, 26 June 2019
Specific trends, such as melting point and atomic radius, recur periodically among the elements when they’re listed in order of increasing atomic weight.
—Bill Andrews, Discover Magazine, 26 June 2019
Cite this Entry
“Atomic weight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/atomic%20weight. Accessed 23 May. 2025.
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